Comparative clinical utility of preoperative psoas muscle and skeletal muscle index cutoffs for risk stratification after esophagectomy

PURPOSE: To compare the clinical utility of preoperative psoas muscle index (PMI) and skeletal muscle index (SMI) cutoff stratification for predicting postoperative pulmonary complications (PPCs) and survival after esophagectomy. METHODS: This single-center retrospective study included 334 patients who underwent esophagectomy for thoracic esophageal cancer. Preoperative SMI and PMI were measured on CT images at the L3 level and classified using established cutoff values. Associations with PPCs were examined using multivariable logistic regression. The 5-year overall survival (OS) and recurrence-free survival (RFS) rates were evaluated. RESULTS: PPCs occurred in 110 patients in the study. The low-PMI group had significantly higher rates of PPCs and pneumonia than the no low-PMI group, whereas no significant differences were observed between the SMI-based groups. In a multivariable analysis, a low PMI was independently associated with PPCs (OR 2.17, 95% CI 1.16-4.07; p = 0.02), but a low SMI was not. The low-PMI group showed worse 5-year OS and RFS in unadjusted analyses, whereas SMI was not associated with these outcomes. In Cox regression analyses adjusted for other prognostic factors, the association between a low PMI and long-term outcomes was attenuated. CONCLUSIONS: The preoperative PMI was more strongly associated with PPCs after esophagectomy than SMI. Although unadjusted analyses indicated an association, a low-PMI did not independently predict worse long-term outcomes in the adjusted analyses.